IntroductionOne of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells.PurposeIn this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo.Materials and methodsThe Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet–visible, and Fourier transform infrared.ResultsWe show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and a clinical multidrug-resistant strain of P. aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the results demonstrate that Ag-NPs can be used safely as therapeutic agents in animal models.ConclusionTogether, these results suggest the potential use of Ag-NPs, synthesized by green chemistry methods, as therapeutic agents against infections caused by resistant and nonresistant strains.
Copper nanoparticles (CuNP) were obtained by a green synthesis method using cotton textile fibers and water as solvent, avoiding the use of toxic reducing agents. The new synthesis method is environmentally friendly, inexpensive, and can be implemented on a larger scale. This method showed the cellulose capacity as a reducing and stabilizing agent for synthetizing Cellulose–Copper nanoparticles (CCuNP). Nanocomposites based on CCuNP were characterized by XRD, TGA, FTIR and DSC. Functional groups present in the CCuNP were identified by FTIR analysis, and XRD patterns disclosed that nanoparticles correspond to pure metallic Cu°, and their sizes are at a range of 13–35 nm. Results demonstrated that CuNPs produced by the new method were homogeneously distributed on the entire surface of the textile fiber, obtaining CCuNP nanocomposites with different copper wt%. Thus, CuNPs obtained by this method are very stable to oxidation and can be stored for months. Characterization studies disclose that the cellulose crystallinity index (CI) is modified in relation to the reaction conditions, and its chemical structure is destroyed when nanocomposites with high copper contents are synthesized. The formation of CuO nanoparticles was confirmed as a by-product, through UV spectroscopy, in the absorbance range of 300–350 nm.
Micrometer-sized composite polymer-magnetic spheres consisting of a magnetic-spherical core with a polystyrene shell were produced. The magnetic-spherical core was produced by plasma thermal conversion of waste powders precursor (iron oxide) generated during the conventional process of steel production. Precursor powders were projected into an Ar-He plasma plume using industrial thermal-spray equipment. The results are a total conversion of the precursor powders into magnetic-spherical particles with diameters in the micrometer size range. The surfaces of the magnetic-spheres were functionalized by a chemistry hydrolysis method using 3-aminopropyltrimethoxysilane (APTMS) and creating superficial amine structures that improved the adherence of the final polystyrene shells that was polymerized by adapting the miniemulsion process. The products at the different synthesis steps were characterized by diverse techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), Fourier Transformed Infrared spectroscopy (FTIR) and the magnetic properties were investigated with a vibrating sample magnetometer.
The viscoelastic and mechanical performance of sustainable raw materials on biodegradable matrices provide insights into how to develop and improve materials that contribute to the circular economy. Thus, we aim to evaluate the effect of conventional (acid or alkali) and dual (alkali/acid‐ultrasound) treatment on Agave fibers, as well as their rheological and micromechanical performance on polyvinyl alcohol (PVA)‐based composites. TGA results indicate that the treatments promote the removal of moisture, waxes, pectin, hemicellulose, and lignin from the fibers to different extents. PVA matrix containing modified fibers exhibits low viscosity, flux index, and critical shear values, indicating a high interaction and dispersion of the filler in the matrix. Furthermore, tensile tests and theoretical predictions of micromechanics‐based finite element analysis show evidence that the modified fiber type provides a different stress transfer ratio () than in the matrix, which changes Young's modulus values. The results indicate that Agave fibers modified by dual treatment are a useful filler to produce soft or stiff PVA composites when looking for potential applications in the mobility industry or other fields like the packaging.
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